VEGETATION OF DESERT MOUNTAINS 



303 



The answer to the first of these problems was not wholly lost 

 by the failure of the record at 10,000 feet, as the maximum rain- 

 fall was registered at 7000 feet and there was a progressive fall 

 up to 9000 feet, this station having nearly the same reading as 

 the one at 6000 feet. In 1917 the rainfall at Bonita, near the 



Fig. 7. Graphs showing the relation of altitude to rainfall in the Santa Cata- 

 lina Mountains (heavy line) and Pinaleno Mountains (light line) for the summer 

 of 1917. 



base of the Pinalenos, was slightly less than at Willcox, 35 miles 

 away near the centre of the bolson, although Bonita is nearly 

 1000 feet higher than Willcox. At the first mountain station, 

 however, the rainfall was more than twice as great as the fall 



